Variable-speed speed-up mechanism

ABSTRACT

A variable-speed speed-up mechanism includes: an electric device generating a rotation driving force; and a transmission device changing a speed of the rotation driving force and transmitting the rotation driving force to a target to be driven. The transmission device includes: a sun gear rotating around an axis line; a sun gear shaft fixed to the sun gear and extending in an axial direction around the axis line; a planetary gear meshing with the sun gear, revolving around the axis line, and rotating around a center line of the planetary gear; a gear meshing with the planetary gear; a planetary gear carrier including a planetary gear carrier shaft extending in the axial direction around the axis line and supporting the planetary gear; and a gear carrier including a gear carrier shaft extending in the axial direction around the axis line and supporting the gear.

TECHNICAL FIELD

The present invention relates to a variable-speed speed-up mechanism, including: an electric device including a constant-speed electric motor and a variable-speed electric motor; and a planetary gear transmission device which changes a rotation driving force generated by the electric device and transmits a target to be driven.

BACKGROUND ART

As a device which drives a rotary machine, such as a compressor, there are an electric device which generates a rotation driving force and a transmission device which changes the speed of the rotation driving force generated by the electric device and transmits the rotation driving force to the rotary machine.

Patent Document 1 describes that a constant-speed electric motor and a variable-speed electric motor for speed change are used as the electric device and a planetary gear transmission device is used as the transmission device in order to accurately control a gear ratio. In the device, by changing the rotational speed of the variable-speed electric motor, it is possible to change the rotational speed of an output shaft of the planetary gear transmission device connected to the rotary machine.

CITATION LIST Patent Literature

[PATENT DOCUMENT 1] Japanese Patent No. 4472350

SUMMARY OF INVENTION Technical Problem

For example, in a case of driving the compressor using the above-described variable-speed speed-up mechanism, it is not preferable to reversely rotate the output shaft of the planetary gear transmission device. However, for example, when the rotation of the output shaft is stopped, there is a possibility that the output shaft reversely rotates.

An object of the present invention relates to providing a variable-speed speed-up mechanism including: an electric device including a constant-speed electric motor and a variable-speed electric motor; and a planetary gear transmission device which changes the speed of the rotation driving force generated by the electric device and transmits the rotation driving force to a target to be driven, in which it is possible to prevent an output shaft of the planetary gear transmission device from reversely rotating.

According to one aspect of the present invention, a variable-speed speed-up mechanism, there is provided an electric device which is configured to generate a rotation driving force; and a transmission device which is configured to change the speed of the rotation driving force generated by the electric device and to transmit the rotation driving force to a target to be driven, in which the transmission device includes a sun gear which is configured to rotate around an axis line, a sun gear shaft which is fixed to the sun gear and extends in a axial direction around the axis line, a planetary gear which is configured to mesh with the sun gear and to revolve around the axis line and to rotate around a center line thereof, a gear of which a plurality of teeth are arranged in an annular shape around the axis line, and which is configured to mesh with the planetary gear, a planetary gear carrier which has a planetary gear carrier shaft that extends in the axial direction around the axis line and supports the planetary gear to be capable of revolving around the axis line and to be rotatable around the center line of the planetary gear itself, and a gear carrier which has a gear carrier shaft that extends in the axial direction around the axis line and supports the gear to be rotatable around the axis line, in which the sun gear shaft forms an output shaft which is configured to connect to the target to be driven, the gear carrier shaft forms a constant-speed input shaft, and the planetary gear carrier shaft forms a variable-speed input shaft, in which the electric device includes a constant-speed electric motor having a constant-speed rotor that rotates the constant-speed input shaft of the transmission device in a second direction, a variable-speed electric motor having a variable-speed rotor which is connected to the variable-speed input shaft of the transmission device, which rotates the output shaft at the maximum rotational speed by rotating the variable-speed rotor at the maximum rotational speed in a first direction opposite to the second direction, at least two rotational speed sensors among an output shaft rotational speed sensor which measures a rotational speed ωs of the output shaft, a variable-speed electric motor rotational speed sensor which measures a rotational speed ωh of the variable-speed electric motor, and a constant-speed electric motor rotational speed sensor which measures a rotational speed ωi of the constant-speed electric motor, and a control device capable of calculating the rotational speed ωs of the output shaft and the rotational speed ωh of the variable-speed electric motor from a measured value of the rotational speed sensor, and in which, when a ratio ωs/ωi of the rotational speed ωs of the output shaft to the rotational speed ωi of the constant-speed electric motor is U, and when a ratio ωc/ωh of a rotational speed ωc of the planetary gear carrier to the rotational speed ωh of the variable-speed electric motor is P, in a case of ωs<0, the control device calculates a command value ωh′ of the rotational speed of the variable-speed electric motor to satisfy ωh′=ωh−ωs/P/(1+U), and controls the variable-speed electric motor by the command value ωh′.

With such a configuration, it is possible to prevent the output shaft from reversely rotating.

In the variable-speed speed-up mechanism, in a case of ωs/P/(1+U)<ωh, the control device may calculate the command value ωh′ of the rotational speed of the variable-speed electric motor to satisfy ωh′=ωs/P/(1+U), and may control the variable-speed electric motor by the command value ωh′.

With such a configuration, it is possible to prevent the constant-speed electric motor from reversely rotating.

In the variable-speed speed-up mechanism, the variable-speed rotor may have a cylindrical shape around the axis line and the constant-speed input shaft may be inserted into a shaft insertion hole penetrating in an axial direction.

In the variable-speed speed-up mechanism, the gear may be an internal gear, and the gear carrier shaft may be an internal gear carrier shaft.

In the variable-speed speed-up mechanism, the gear may be an external gear, the gear carrier shaft may be an external gear carrier shaft, the planetary gear may include a primary gear which meshes with the external gear and a secondary gear which meshes with the sun gear, and the planetary gear carrier coaxially may support the primary gear and the secondary gear.

Advantageous Effects of Invention

According to the present invention, it is possible to prevent the output shaft of the variable-speed speed-up mechanism from reversely rotating.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view of a variable-speed speed-up mechanism of a first embodiment according to the present invention.

FIG. 2 is a sectional view of a gear transmission device of the first embodiment according to the present invention.

FIG. 3 is a sectional view of an electric device of the first embodiment according to the present invention.

FIG. 4 is a schematic view illustrating a configuration of the gear transmission device of the first embodiment according to the present invention.

FIG. 5 is a flowchart illustrating an operation of a control unit of the embodiment of the present invention.

FIG. 6 is a schematic view illustrating a configuration of a transmission device of a second embodiment according to the present invention.

DESCRIPTION OF EMBODIMENTS First Embodiment

Hereinafter, a variable-speed speed-up mechanism of an embodiment of the present invention will be described in detail with reference to the drawings.

As illustrated in FIG. 1, a variable-speed speed-up mechanism 1 of the embodiment includes an electric device 50 which generates a rotation driving force, and a transmission device 10 which changes the speed of the rotation driving force generated by the electric device 50 and transmits the rotation driving force to a target to be driven. The variable-speed speed-up mechanism 1 can be employed in, for example, a fluid mechanical system, such as a compressor system.

The target to be driven of the variable-speed speed-up mechanism 1 of the present embodiment is a compressor C.

The gear transmission device 10 is a planetary gear transmission device.

The electric device 50 includes a constant-speed electric motor 51 having a constant-speed rotor 52 which rotates at a constant-speed, and a variable-speed electric motor 71 having a variable-speed rotor 72 which rotates at any rotational speed. The constant-speed rotor 52 and the variable-speed rotor 72 are each connected to the transmission device 10.

The electric device 50 is supported by a frame 90 by an electric device support unit 50S. The gear transmission device 10 is supported by the frame 90 by a transmission device support unit 10S. By the support units, it is possible to reliably fix the electric device 50 and the gear transmission device 10, which are heavy objects.

As illustrated in FIG. 2, the transmission device 10 includes a sun gear 11 which rotates around an axis line Ar that extends in a horizontal direction, a sun gear shaft 12 which is fixed to the sun gear 11, a plurality of planetary gears 15 which mesh with the sun gear 11, revolve around the axis line Ar, and rotate around a center line Ap thereof, an internal gear (gear) 17 of which a plurality of teeth are arranged in an annular shape around the axis line Ar, and which meshes with the plurality of planetary gears 15, a planetary gear carrier 21 which supports the plurality of planetary gears 15 to be capable of revolving around the axis line Ar and to be rotatable around a center line Ap of the planetary gear 15 itself, an internal gear carrier (gear carrier) 31 which supports the internal gear 17 to be rotatable around the axis line Ar, and a transmission device casing 41 which covers the members.

Hereinafter, a direction in which the axis line Ar extends is an axial direction, one side in the axial direction is an output side, and the side opposite to the output side is an input side. In addition, a radial direction around the axis line Ar is simply referred to as a radial direction. In the variable-speed speed-up mechanism 1 of the present embodiment, the electric device 50 is disposed on the input side in the axial direction in the variable-speed speed-up mechanism 1, and the gear transmission device 10 is disposed on the output side with respect to the electric device 50. The compressor C is disposed on the output side with respect to the variable-speed speed-up mechanism 1.

The sun gear shaft 12 forms a columnar shape around the axis line Ar, and extends from the sun gear 11 to the output side in the axial direction. A flange 13 is formed in an output side end portion of the sun gear shaft 12. For example, a rotor of the compressor C that serves as a target to be driven is connected to the flange 13. The sun gear shaft 12 is supported by a sun gear bearing 42 disposed on the output side with respect to the sun gear 11 so as to be rotatable around the axis line Ar. The sun gear bearing 42 is attached to the transmission device casing 41.

The planetary gear carrier 21 includes a planetary gear shaft 22 provided for each of the plurality of planetary gears 15, a planetary gear carrier main body 23 for fixing positions of the plurality of planetary gear shafts 22 with each other, and an output side planetary gear carrier shaft 27 o which extends in the axial direction around the axis line Ar. The output side planetary gear carrier shaft 27 o is fixed to inner side in the radial direction of the planetary gear carrier main body 23.

The planetary gear shaft 22 penetrates the center line Ap of the planetary gear 15 in the axial direction and supports the planetary gear 15 so as to be rotatable around the center line thereof. The planetary gear carrier main body 23 extends radially outward from the plurality of planetary gear shafts 22.

The output side planetary gear carrier shaft 27 o extends outward from the planetary gear carrier main body 23. The output side planetary gear carrier shaft 27 o forms a cylindrical shape around the axis line Ar.

The output side planetary gear carrier shaft 27 o is supported by a planetary gear carrier bearing 43 so as to be rotatable around the axis line Ar. The planetary gear carrier bearing 43 is attached to the transmission device casing 41. The sun gear shaft 12 is inserted into an inner circumferential side of the output side planetary gear carrier shaft 27 o.

The transmission device 10 includes an input side planetary gear carrier shaft 27 i connected to the variable-speed rotor 72 of the variable-speed electric motor 71, and a transmission device shaft 25 which transmits the rotation of the input side planetary gear carrier shaft 27 i to the planetary gear carrier 21.

The input side planetary gear carrier shaft 27 i forms a cylindrical shape around the axis line Ar. The input side planetary gear carrier shaft 27 i is disposed on the input side of the transmission device 10, and is supported by a planetary gear carrier bearing 44 so as to be rotatable around the axis line Ar. The planetary gear carrier bearing 44 is attached to the transmission device casing 41. An internal gear carrier shaft 37 for driving the internal gear carrier 31 of the transmission device 10 is inserted into the inner circumferential side of the input side planetary gear carrier shaft 27 i.

An annular flange 28 which widens radially outward is formed at an input side end of the input side planetary gear carrier shaft 27 i. An input side arm portion 26 which extends radially outward is formed at an output side end of the input side planetary gear carrier shaft 27 i.

The transmission device shaft 25 is supported so as to be rotatable around an axis line At. The transmission device shaft 25 is attached to the transmission device casing 41 via a bearing (not illustrated). At both ends of the transmission device shaft 25, an input side transmission device gear 29 i and an output side transmission device gear 29 o are fixed.

The input side transmission device gear 29 i meshes with a gear formed at an outer circumference of the input side arm portion 26. The output side transmission device gear 29 o meshes with a gear formed at the outer circumference of the planetary gear carrier main body 23. Accordingly, the rotation of the input side planetary gear carrier shaft 27 i is transmitted to the planetary gear carrier 21 via the transmission device shaft 25.

The internal gear carrier 31 includes a carrier main body 33 to which the internal gear 17 is fixed, and an internal gear carrier shaft 37 which is fixed to the carrier main body 33 and extends in the axial direction around the axis line Ar.

The carrier main body 33 includes a cylinder portion 35 which forms a cylindrical shape around the axis line Ar and has the internal gear 17 fixed to the inner circumferential side thereof, and an input side arm portion 36 which extends radially inward from the input side end of the cylinder portion 35.

The internal gear carrier shaft 37 having a columnar shape around the axis line Ar is disposed on the input side with respect to the sun gear shaft 12 having a columnar shape around the axis line Ar. The input side arm portion 36 of the carrier main body 33 is fixed to the internal gear carrier shaft 37. The internal gear carrier shaft 37 is inserted into the inner circumferential side of the cylindrical input side planetary gear carrier shaft 27 i.

As illustrated in FIG. 3, the constant-speed electric motor 51 rotates and drives the internal gear carrier shaft 37 of the gear transmission device 10. The variable-speed electric motor 71 rotates and drives the input side planetary gear carrier shaft 27 i of the gear transmission device 10. The electric device 50 includes a cooling fan 91 for cooling the constant-speed electric motor 51 and a fan cover 92 which covers the cooling fan 91.

The internal gear carrier shaft 37 is a constant-speed input shaft Ac which rotates at a constant-speed by a driving force of the constant-speed electric motor 51. The input side planetary gear carrier shaft 27 i is a variable-speed input shaft Av which rotates at any rotational speed by a driving force of the variable-speed electric motor 71.

In the variable-speed speed-up mechanism 1, by changing the rotational speed of the variable-speed electric motor 71, it is possible to change the rotational speed of an output shaft Ao of the gear transmission device 10 connected to the target to be driven.

In the present embodiment, the constant-speed electric motor 51 is, for example, a four-pole three-phase induction electric motor. In addition, the variable-speed electric motor 71 is a six-pole three-phase induction electric motor having more poles than the constant-speed electric motor 51. In addition, the specifications of the constant-speed electric motor 51 and the variable-speed electric motor 71 are not limited thereto, and specifications can be appropriately changed.

The constant-speed electric motor 51 includes a constant-speed rotor 52 which rotates around the axis line Ar and is connected to the internal gear carrier shaft 37 which is the constant-speed input shaft Ac of the transmission device 10, a constant-speed stator 66 which is disposed on the outer circumferential side of the constant-speed rotor 52, and a constant-speed electric motor casing 61 to which the constant-speed stator 66 is fixed to the inner circumferential side.

The constant-speed rotor 52 includes a constant-speed rotor shaft 53 which forms a columnar shape around the axis Ar, and a conductor 56 which is fixed to the outer circumference of the constant-speed rotor shaft 53. The cooling fan 91 is fixed to the input side end of the constant-speed rotor shaft 53.

The constant-speed stator 66 is disposed on the radial outside of the conductor 56 of the constant-speed rotor 52. The constant-speed stator 66 is formed of a plurality of coils.

The constant-speed electric motor casing 61 includes a casing main body 62 having a cylindrical shape around the axis line Ar and having a constant-speed stator 66 fixed to the inner circumferential side thereof, and lids 63 i and 63 o which blocks both ends of the cylindrical casing main body 62 in the axial direction. Constant-speed rotor bearings 65 i and 65 o which rotatably support the constant-speed rotor shaft 53 around the axis line Ar are attached to each of the lids 63 i and 63 o. A plurality of openings 64 which penetrate in the axial direction are formed in each of the lids 63 i and 63 o at positions further on the radial outside than the constant-speed rotor bearing 65 i.

The input side end of the constant-speed rotor shaft 53 protrudes to the input side from the lid 63 i on the input side of the constant-speed electric motor casing 61. The cooling fan 91 is fixed to the input side end of the constant-speed rotor shaft 53.

When the constant-speed rotor 52 rotates, the cooling fan 91 also rotates integrally with the constant-speed rotor 52. The fan cover 92 includes a cylindrical cover main body 93 which is disposed on the outer circumferential side of the cooling fan 91, and an air-circulating plate 94 which is attached to the opening on an inlet side of the cover body 93 and which has a plurality of air holes formed therein. The fan cover 92 is fixed to the lid 63 i on the input side of the constant-speed electric motor casing 61.

The variable-speed electric motor 71 includes a variable-speed rotor 72 which rotates around the axis line Ar and is connected to the input side planetary gear carrier shaft 27 i which is the variable-speed input shaft Av, a variable speed stator 86 which is disposed on the outer circumferential side of the variable-speed rotor 72, and a variable-speed electric motor casing 81 to which the variable speed stator 86 is fixed on the inner peripheral side.

The variable-speed rotor 72 includes a variable-speed rotor shaft 73 and a conductor 76 which is fixed to the outer circumference of the variable-speed rotor shaft 73. The variable-speed rotor shaft 73 has a cylindrical shape around the axis line Ar and has a shaft insertion hole 74 which penetrates in the axial direction. The internal gear carrier shaft 37 which is the constant-speed input shaft Ac is inserted into the shaft insertion hole 74 of the variable-speed rotor shaft 73. An annular flange 73 o which widens radially outward is formed at the output side end of the variable-speed rotor shaft 73.

The variable speed stator 86 is disposed on the radial outside of the conductor 76 of the variable-speed rotor 72. The variable speed stator 86 is formed of a plurality of coils.

The variable-speed electric motor casing 81 includes a casing main body 82 having a cylindrical shape around the axis line Ar and having the variable speed stator 86 fixed to the inner circumferential side thereof, an output side lid 83 o which blocks the output side end of the cylindrical casing main body 82, and an inlet side lid 83 i which is disposed further on the input side than the variable speed stator 86 and is fixed to the inner circumferential side of the cylindrical casing main body 82. Variable-speed rotor bearings 85 i and 85 o which rotatably support the variable-speed rotor shaft 73 around the axis line Ar are attached to each of the lids 83 i and 83 o. A plurality of openings 84 which penetrate in the axial direction are formed in each of the lids 83 i and 83 o at positions further on the radial outside than the variable-speed rotor bearings 85 i and 85 o.

By the plurality of openings 84 being formed in the each of lids 83 i and 83 o of the variable-speed electric motor casing 81 and the plurality of openings 64 being formed in each of the lids 63 i and 63 o of the constant-speed electric motor casing 61, a space in the variable-speed electric motor casing 81 and a space in the constant-speed electric motor casing 61 communicate with each other.

In addition, in the variable-speed speed-up mechanism 1 of the present embodiment, the constant-speed rotor 52, the variable-speed rotor 72, and the sun gear shaft 12 are arranged on the same axis line Ar.

As illustrated in FIG. 4, the constant-speed electric motor 51 is set so as to rotate the constant-speed rotor 52 (internal gear 17) in a second direction R2 in the circumferential direction of the axis line Ar by supplying electric power to the constant-speed electric motor 51. As the constant-speed rotor 52 rotates in the second direction R2, the internal gear carrier shaft 37 and the internal gear carrier 31 rotate in the second direction R2.

The output shaft Ao of the transmission device 10 is provided so as to rotate in the first direction R1 reverse to the second direction R2 as the constant-speed rotor 52 of the constant-speed electric motor 51 rotates at the maximum rotational speed in the second direction R2. In other words, the forward rotation of the constant-speed electric motor 51 is performed in the second direction R2, and the forward rotation of the output shaft Ao of the transmission device 10 is performed in the first direction R. The compressor C operates normally as the output shaft Ao rotates forward.

In the following description, the rotational direction in the first direction R1 is defined as a positive rotational direction, and the rotational direction in the second direction R2 is defined as a negative rotational direction. For example, the maximum rotational speed of the constant-speed electric motor 51 is −1800 rpm.

The variable-speed electric motor 71 can rotate and drive the variable-speed rotor 72 (planetary gear carrier 21) in the first direction R1 and in the second direction R2 in the circumferential direction of the axis line Ar. In other words, the variable-speed electric motor 71 is capable of rotating forward and reversely.

The variable-speed electric motor 71 functions as a generator by rotating the variable-speed rotor 72 in the second direction R2. A state where the variable-speed electric motor 71 functions as a generator is referred to as a generator mode. In other words, the variable-speed rotor 72 of the variable-speed electric motor 71 rotates in the second direction R2 in the generator mode.

The variable-speed electric motor 71 functions as a electric motor by rotating the variable-speed rotor 72 in the first direction R1. A state where the variable-speed electric motor 71 functions as the electric motor is referred to as an electric motor mode. In other words, the variable-speed rotor 72 of the variable-speed electric motor 71 rotates in the first direction R1 in the electric motor mode.

As the variable-speed rotor 72 rotates in the first direction R1, the planetary gear carrier 21 rotates in the first direction R1.

The variable-speed speed-up mechanism 1 of the present embodiment includes: a rotational speed control device 100 which controls the rotational speed of the variable-speed electric motor 71; a variable-speed electric motor switch 111 which sets the variable-speed electric motor 71 in a power supply state and in a power cut state; a constant-speed electric motor switch 112 which sets the constant-speed electric motor 51 in a power supply state and in a power cut state; and a control unit 120 which controls operations of the rotational speed control device 100, the variable-speed electric motor switch 111, and the constant-speed electric motor switch 112.

The control unit 120 is configured with a computer. The control unit 120 includes: a reception unit 121 which directly receives an instruction from an operator or receives an instruction from a host control device; an interface 122 which gives the instruction to the variable-speed electric motor switch 111, the rotational speed control device 100, and the constant-speed electric motor switch 112; and an operation unit 123 which prepares the instruction to the variable-speed electric motor switch 111, the constant-speed electric motor switch 112, and the rotational speed control device 100 in accordance with the instruction or the like received by the reception unit 121.

The variable-speed electric motor switch 111 is electrically connected to a power source line 110 and the rotational number control device 100. The rotational speed control device 100 is electrically connected to the variable-speed electric motor 71. The constant-speed electric motor switch 112 is electrically connected to the power source line 110 and the constant-speed electric motor 51.

The variable-speed electric motor switch 111 is turned on by an ON instruction from the control unit 120, and is turned off by an OFF instruction from the control unit 120. When the variable-speed electric motorswitch 111 is turned on, the electric power from the power source line 110 is supplied to the variable-speed electric motor 71 via the rotational speed control device 100, and the variable-speed electric motor 71 is placed in the power supply state. When the variable-speed electric motor switch 111 is turned on, the electric power from the power source line 110 is supplied to the rotational speed control device 100 and the variable-speed electric motor 71, and the variable-speed electric motor 71 is placed in the power cut state.

The constant-speed electric motor switch 112 is turned on by an ON instruction from the control unit 120, and is turned off by an OFF instruction from the control unit 120. When the constant-speed electric motor switch 112 is turned on, the electric power from the power source line 110 is supplied to the constant-speed electric motor 51, and the constant-speed electric motor 51 is placed in the power supply state. When the constant-speed electric motor switch 112 is turned off, the electric power from the power source line 110 is supplied to the constant-speed electric motor 51, and the constant-speed electric motor 51 is placed in the power cut state.

The rotational speed control device 100 includes a frequency conversion unit 101 which changes the frequency of electric power supplied from the power source line 110, and a rotational direction-changing unit 102 which changes the rotational direction of the variable-speed electric motor 71.

The frequency conversion unit 101 supplies the power of the frequency instructed from the control unit 120 to the variable-speed electric motor 71. The variable-speed rotor 72 of the variable-speed electric motor 71 rotates at a rotational speed that corresponds to the frequency. In this manner, since the rotational speed of the variable-speed rotor 72 changes, the rotational speed of the planetary gear carrier 21 of the transmission device 10 connected to the variable-speed rotor 72 also changes. As a result, the rotational speed of the sun gear shaft 12 which is the output shaft Ao of the transmission device 10 also changes.

The rotational direction-changing unit 102 is a device which changes the rotational direction of the variable-speed electric motor 71 by using a circuit for switching a plurality of (three in the case of the present embodiment) power source lines connected to the variable-speed electric motor 71. In other words, the rotational direction-changing unit 102 can rotate the variable-speed rotor 72 forward and reverse.

The variable-speed speed-up mechanism 1 of the present embodiment is provided with an output shaft rotational speed sensor 131 which measures the rotational speed of the output shaft Ao. In addition, the variable-speed speed-up mechanism 1 of the present embodiment is provided with a constant-speed electric motor rotational speed sensor 132 which measures the rotational speed of the constant-speed electric motor 51 (constant-speed rotor 52). In addition, the variable-speed speed-up mechanism 1 of the present embodiment is provided with a variable-speed electric motor rotational speed sensor 133 which measures the rotational speed of the variable-speed electric motor 71 (variable-speed rotor 72). The rotational speed measured by the rotational speed sensors is transmitted to the control unit 120.

Based on the measured value measured by the rotational speed sensor, the control unit 120 of the variable-speed speed-up mechanism 1 of the present embodiment has a function of preventing a rotation shaft of the compressor C connected to the output shaft Ao and the output shaft Ao from rotating reversely (rotation in the second direction R2), and has a function of preventing the constant-speed rotor 52 from rotating reversely (rotation in the first direction R1).

Here, the relationship between the number of teeth of each gear of the transmission device 10 and the rotational speed of each shaft of the transmission device 10 will be described with reference to FIG. 4.

The rotational speed of the sun gear shaft 12 that serves as the output shaft Ao is ωs, the rotational speed of the internal gear carrier shaft 37 (constant-speed electric motor 51) that serves as the constant-speed input shaft Ac is ωi, and the rotational speed of the input side planetary gear carrier shaft 27 i (variable-speed electric motor 71) that serves as the variable-speed input shaft Av is ωh. In addition, the number of teeth of the sun gear 11 is Zs, and the number of teeth of the internal gear 17 is Zi.

In addition, a ratio ωs/ωi of the rotational speed ωs of the output shaft Ao to the rotational speed ωi of the constant-speed electric motor 51 is U. The ratio U of the rotational speed ωs of the output shaft Ao to the rotational speed ωi of the constant-speed electric motor 51 is the same as a ratio Zi/Zs of the number of teeth Zi of the internal gear 17 to the number of teeth Zs of the sun gear 11.

In addition, a ratio ωc/ωh of the rotational speed ωc of the planetary gear carrier 21 to the rotational speed ωh of the variable-speed electric motor 71 is P.

The relationship between the number of teeth of each of the gears and the rotational speed of each of the shafts of the transmission device 10 can be expressed by the following expression (1). ωs/ωi=P×ωh/ωi−(1−P×ωh/ωi)×U  (1)

In a case where the constant-speed electric motor 51 is a four-pole induction electric motor and the power supply frequency is 60 Hz, the rotational speed ωi (rated rotational speed) of the constant-speed rotor 52 (constant-speed input shaft Ac) is 1800 rpm. In addition, in a case where the variable-speed electric motor 71 is an eight-pole induction electric motor and the power supply frequency is 60 Hz, the highest rotational speed ωh (rated rotational speed) of the variable-speed rotor 72 (variable-speed input shaft Av) is 900 rpm.

In addition, the ratio U of the rotational speed ωs of the output shaft Ao to the rotational speed ωi of the constant-speed electric motor 51 (the ratio Zi/Zs of the number of teeth Zs of the sun gear 11 to the number of teeth Zs the internal gear 17) is 4.

In addition, the ratio P of the rotational speed ωc of the planetary gear carrier 21 to the rotational speed ωh of the variable-speed electric motor 71 is 0.3.

In this case, when the direction of rotation of the constant-speed rotor 52 (internal gear 17) is defined as rotation in the second direction R2 (−1800 rpm) and the direction of rotation of the variable-speed rotor 72 (planetary gear carrier 21) is defined as the highest rotational speed (900 rpm) in a direction (rotation in the first direction R1) reverse to the rotation of the constant-speed rotor 52, the rotational speed ωs of the sun gear shaft 12 which is the output shaft Ao is 11700 rpm. The rotational speed (11700 rpm) is the highest rotational speed of the sun gear shaft 12.

In other words, in the transmission device 10 of the present embodiment, the internal gear 17 that corresponds to the constant-speed input shaft Ac rotates at 1800 rpm and the planetary gear carrier 21 that corresponds to the variable-speed input shaft Av rotates at 900 rpm, and accordingly, the rotational speed ωs of the output shaft Ao becomes the highest rotational speed.

When assuming that the variable speed range of the variable-speed input shaft Av is from −900 rpm to +900 rpm, as the rotational speed of the variable-speed input shaft Av approaches −900 rpm, the rotational speed ωs of the output shaft Ao gradually decreases.

In a case where the rotational speed of the constant-speed rotor 52 (rated rotational speed) is 1800 rpm and the rotational speed of the variable-speed rotor 72 in the electric motor mode is controlled within the range of 300 to 900 rpm by frequency control by the frequency conversion unit 101, that is, in a case where the frequency of the electric power to be supplied to the variable-speed electric motor 71 is controlled within the range of 16.7 Hz to 60 Hz, the rotational speed of the sun gear shaft 12 which is the output shaft Ao can be controlled to the range of 8700 to 11700 rpm. The range is a variable speed range of the sun gear shaft 12 which is the output shaft Ao of the variable-speed speed-up mechanism 1, and the variable-speed speed-up mechanism 1 generally rotates the output shaft Ao within the variable speed range.

However, in particular, when stopping the rotation of the output shaft Ao of the variable-speed speed-up mechanism 1, that is, when lowering the rotational speed ωi of the constant-speed electric motor 51 and the rotational speed ωh of the variable-speed electric motor 71, there is a possibility that the output shaft Ao rotates reversely (rotation in the second direction R2) or the constant-speed electric motor 51 rotates reversely (rotation in the first direction R1).

As described above, the control unit 120 of the present embodiment has a function of preventing the reverse rotation.

Next, the variable-speed speed-up mechanism 1 of the present embodiment will be described.

Here, the conditions for setting the rotational direction of the constant-speed electric motor 51 and the output shaft Ao in the positive direction will be described. The control unit 120 of the variable-speed speed-up mechanism 1 refers to the condition.

First, since it is necessary to set the rotational direction of the rotational speed ωs of the output shaft Ao as the first direction R1, the condition expressed by the following expression (2) is determined. ωs≥0  (2)

In addition, since the rotational direction of the rotational speed ωi of the constant-speed electric motor 51 is the second direction R2 opposite to the first direction R1, the condition expressed by the following expression (3) is determined. ωi≤0  (3)

In other words, in the variable-speed speed-up mechanism 1 of the present embodiment, it is always necessary to satisfy the expressions (2) and (3).

In addition, as described above, the relationship between the number of teeth of each of the gears and the rotational speed of each of the shafts of the transmission device 10 can be expressed by the following expression (1). ωs/ωi=P×ωh/ωi−(1−P×ωh/ωi)×U  (1)

When the expression (1) is solved for ωs, ωs=P×(U+1)ωh−U×ωi  (4)

is satisfied. Furthermore, when the expression (4) is solved for ωi, U×ωi=P×(U+1)ωh−ωs ωi=P×ωh×(U+1)/U−ωs/U  (5) is satisfied.

From the expression (4) and the expression (2), which is a condition related to the output shaft Ao, the following expression (6) is derived. (1+U)×P×ωh−U×ωi≥0  (6)

When the command value of the rotational speed of the variable-speed electric motor 71 for satisfying the expression (6) is ωh′, it can be understood that the command value ωh′ needs to satisfy the following expression (7).

[Number 1]

$\begin{matrix} {{\omega\; h^{\prime}} \leq {\frac{U}{P\left( {U + 1} \right)}\omega\; i}} & (7) \end{matrix}$

By substituting the equation (5) into equation (7) and deleting ωi, the following equation (8) is derived.

[Number 2]

$\begin{matrix} {{{{\omega\; h^{\prime}} \geqq {\frac{U}{P\left( {U + 1} \right)}\omega\; i}} = {\frac{U}{P\left( {U + 1} \right)}\left( {\frac{{P\left( {U + 1} \right)}\omega\; h}{U} - \frac{\omega\; s}{U}} \right)}}{{\omega\; h^{\prime}} \geqq {{\omega\; h} - {\frac{1}{P\left( {U + 1} \right)}\omega\; s}}}} & (8) \end{matrix}$

Similarly, when the command value of the rotational speed of the variable-speed electric motor 71 for keeping the rotational speed ωi of the constant-speed electric motor 51 at the forward rotation is ωh′ from the expressions (3) and (5), it can be understood that it is necessary for the command value ωh′ to satisfy the following expression (9).

[Number 3]

$\begin{matrix} {{\omega\; h^{\prime}} \leqq {\frac{1}{P\left( {U + 1} \right)}\omega\; s}} & (9) \end{matrix}$

When the command value of the rotational speed of the variable-speed electric motor 71 for keeping the output shaft Ao and the rotational speed of the constant-speed electric motor 51 at the forward rotation is ωh′ from the expressions (8) and (9), it can be understood that it is necessary to satisfy the following expression (10).

[Number 4]

$\begin{matrix} {{{\omega\; h} - {\frac{1}{P\left( {U + 1} \right)}\omega\; s}} \leqq {\omega\; h^{\prime}} \leqq {\frac{1}{P\left( {U + 1} \right)}\omega\; s}} & (10) \end{matrix}$

Next, a method of controlling the variable-speed speed-up mechanism 1 of the present embodiment will be described.

The method of controlling the variable-speed speed-up mechanism 1 of the present embodiment includes: a rotational speed-monitoring step S1 for monitoring the rotational speed ωs of the output shaft Ao and the rotational speed ωh of the variable-speed electric motor 71; a first determination step S2 for determining whether or not the rotational number ωs of the output shaft Ao satisfies ωs<0; a first variable-speed electric motor control step S3 for setting the command value ωh′ of the rotational speed of the variable-speed electric motor 71 in a case where the condition of the first determination step S2 is satisfied; a second determination step S4 for determining whether or not the rotational speed ωs of the output shaft Ao and the rotational speed ωh of the variable-speed electric motor 71 satisfy ωs/P/(1+U)<ωh; and a second variable-speed electric motor control step S5 for setting the command value ωh′ of the rotational speed of the variable-speed electric motor 71 in a case where the condition of the second determination step S4 is satisfied.

In the rotational speed-monitoring step S1, the control unit 120 monitors the rotational speed ωs of the output shaft Ao and the rotational speed ωh of the variable-speed electric motor 71.

In the first determination step S2, the control unit 120 determines whether or not the rotational speed ωs of the output shaft Ao satisfies ωs<0. In other words, it is determined whether or not the output shaft Ao is rotating reversely. In a case where the output shaft Ao rotates reversely, the process moves to the first variable-speed electric motor control step S3.

In the first variable-speed electric motor control step S3, the control unit 120 sets the command value ωh′ of the rotational speed of the variable-speed electric motor 71 to ωh′=ωh−ωs/P/(1+U). The control unit 120 rotates the variable-speed electric motor 71 at the command value ωh′. Accordingly, the rotational speed of the output shaft Ao is corrected, and the output shaft Ao does not rotate reversely.

In the second determination step S4, the control unit 120 determines whether or not the rotational speed ωs of the output shaft Ao and the rotational speed ωh of the variable-speed electric motor 71 satisfy ωs/P/(1+U)<ωh. In a case where ωs/P/(1+U)<ωh is satisfied, the process moves to the second variable-speed electric motor control step S5.

In the second variable-speed electric motor control step S5, the control unit 120 sets the command value ωh′ to ωh′=ωs/P/(1+U), and the variable-speed electric motor 71 rotates at the command value ωh′. Accordingly, the rotational speed of the output shaft Ao is corrected, and the constant-speed rotor 52 of the constant-speed electric motor 51 does not rotate reversely.

According to the above-described embodiment, by monitoring the rotational speed ωs of the output shaft Ao and the rotational speed ωh of the variable-speed electric motor 71 to control the rotational speed of the variable-speed electric motor 71, it is possible to prevent the output shaft Ao from rotating reversely. In addition, it is possible to prevent the constant-speed electric motor 51 from rotating reversely.

In addition, in the present embodiment, the internal gear carrier shaft 37 which is a rod-shaped shaft is inserted into the variable-speed rotor shaft 73 which is a cylindrical shaft formed with the shaft insertion hole 74. In other words, the constant-speed input shaft Ac having a large output is inserted into the variable-speed rotor shaft 73 of the variable-speed electric motor 71 having a smaller output than that of the constant-speed electric motor 51. Accordingly, it is possible to adopt a constant-speed electric motor 51 having a larger output (horsepower).

Further, in the present embodiment, since the constant-speed electric motor 51, the variable-speed electric motor 71, the transmission device, and the compressor C are linearly arranged in this order, the whole device can be made more compact.

In addition, in the above-described embodiment, the control unit 120 performs the control by using the rotational speed ωs of the output shaft Ao measured by the output shaft rotational speed sensor 131 and the rotational speed ωh of the variable-speed electric motor 71 measured by the variable-speed electric motor rotational speed sensor 133, but the invention is not limited thereto.

For example, without measuring the rotational speed ωs of the output shaft Ao, the rotational speed ωs of the output shaft Ao may be calculated using the measured value of the rotational speed ωh of the variable-speed electric motor 71 and the rotational speed ωi of the constant-speed electric motor 51.

In a case of calculating the rotational speed ωs of the output shaft Ao using the rotational speed ωh of the variable-speed electric motor 71 and the rotational speed ωi of the constant-speed electric motor 51, the expression (4) can be used.

In addition, in the above-described embodiment, a configuration in which the variable-speed rotor shaft 73 is formed in a cylindrical shape and the internal gear carrier shaft 37 is inserted into the shaft insertion hole 74 of the variable-speed rotor shaft 73 is employed, but the invention is not limited thereto, and for example, the center axis of the variable-speed rotor 72 of the variable-speed electric motor 71 may be offset with respect to the axis line Ar.

In addition, in the above-described embodiment, a four-pole three-phase induction electric motor is exemplified as the constant-speed electric motor 51 that is appropriate for rotating the compressor C at high speed, and a six-pole three-phase induction electric motor is exemplified as the variable-speed electric motor 71 that is appropriate for variably changing the rotational speed of the compressor C within a certain range. However, in a case where it is unnecessary to rotate the target to be driven at high speed, other types of electric motors may be used as the constant-speed electric motor 51 or the variable-speed electric motor 71.

Second Embodiment

Next, with reference to FIG. 6, a transmission device 10A of a second embodiment will be described.

In the second embodiment, the same configuration elements as those of the first embodiment are denoted by the same reference numerals, and the detailed description thereof will be omitted. The internal structure of the transmission device 10A of the second embodiment is different from that of the first embodiment.

In the transmission device 10A of the second embodiment, the gear which was the internal gear in the first embodiment is the external gear. Therefore, the gear carrier shaft which was the internal gear carrier shaft in the first embodiment is the external gear carrier shaft.

Specifically, as illustrated in FIG. 6, the transmission device 10A of the second embodiment includes the sun gear 11, the sun gear shaft 12, a planetary gear 15A, an external gear (gear) 17A, a planetary gear carrier 21A, an external gear carrier (gear carrier) 31A, and the transmission device casing 41 which covers the members.

The planetary gear 15A of the second embodiment includes a plurality of first planetary gears (primary gears) 151A and a plurality of second planetary gears (secondary gears) 152A.

The first planetary gear 151A meshes with the external gear 17A. The first planetary gear 151A revolves around the axis line Ar and also rotates around the center line Ap thereof.

The first planetary gear 152A meshes with the sun gear 11. The second planetary gear 152A revolves around the axis line Ar and also rotates around the center line Ap that is also the same center line as the first planetary gear 151A. The second planetary gear 152A is disposed further on the output side in the axial direction than the first planetary gear 151A. One of the second planetary gears 152A is rotatable integrally with one of the first planetary gears 151A. In other words, one first planetary gear 151A is disposed in a pair with respect to one second planetary gear 152A.

The planetary gear carrier 21A of the second embodiment includes a planetary gear shaft 22A, a planetary gear carrier main body 23A, and a planetary gear carrier shaft 27A.

The planetary gear shaft 22A is provided for each of the plurality of planetary gears 15A. The planetary gear shaft 22A allows the first planetary gear 151A and the second planetary gear 152A which are connected to each other around the center line Ap to be rotatable. The planetary gear shaft 22A connects one second planetary gear 152A to one first planetary gear 151A. Specifically, the first planetary gear 151A is connected to the input side in the axial direction of the planetary gear shaft 22A, and the second planetary gear 152A is connected to the output side in the axial direction of the planetary gear shaft 22A. The planetary gear shaft 22A penetrates the first planetary gear 151A and the second planetary gear 152A in the axial direction. Therefore, an end portion on the input side in the axial direction of the planetary gear shaft 22A is positioned further on the input side in the axial direction than the first planetary gear 151A. In addition, an end portion on the output side in the axial direction of the planetary gear shaft 22A is positioned further on the output side in the axial direction than the second planetary gear 152A.

The planetary gear carrier body 23A fixes mutual positions of the plurality of planetary gear shafts 22A. The planetary gear carrier main body 23A includes a planetary gear output side arm portion 24A and a planetary gear input side arm portion 26A.

The planetary gear output side arm portion 24A rotatably supports the end portion on the output side in the axial direction of the plurality of planetary gear shafts 22A. The planetary gear input side arm portion 26A rotatably supports the end portion on the input side in the axial direction of the plurality of planetary gear shafts 22A. In this manner, by supporting the planetary gear shaft 22A via the planetary gear carrier main body 23A, the planetary gear carrier 21A coaxially supports the first planetary gear 151A and the second planetary gear 152A.

The planetary gear carrier shaft 27A fixes the planetary gear carrier main body 23A. The planetary gear carrier shaft 27A extends in the axial direction around the axis line Ar. The planetary gear carrier shaft 27A includes an output side planetary gear carrier shaft 27Ao which extends from the planetary gear output side arm portion 24A to the output side, and an input side planetary gear carrier shaft 27Ai which extends from the planetary gear input side arm portion 26A to the input side. Both of the output side planetary gear carrier shaft 27Ao and the input side planetary gear carrier shaft 27Ai form a cylindrical shape around the axis line Ar.

The output side planetary gear carrier shaft 27Ao is supported by a planetary gear carrier bearing 43 so as to be rotatable around the axis line Ar with respect to the transmission device casing 41. In the first planetary gear carrier bearing 43, the sun gear shaft 12 is inserted into the inner circumferential side of the output side planetary gear carrier shaft 27Ao disposed further on the output side than the planetary gear output side arm portion 24A.

The input side planetary gear carrier shaft 27Ai is supported by the planetary gear carrier bearing 44 so as to be rotatable around the axis line Ar with respect to the transmission device casing 41. The planetary gear carrier bearing 44 is disposed closer to the input side than the planetary gear input side arm portion 26A. An external gear carrier shaft 37A is inserted into the inner circumferential side of the input side planetary gear carrier shaft 27Ai.

The external gear carrier 31A supports the external gear 17A to be rotatable around the axis line Ar. The external gear carrier 31A includes the external gear carrier shaft 37A connected to the external gear 17A.

The planetary gear carrier shaft 37A is fixed to the external gear 17A and extends in the axial direction around the axis line Ar. The external gear carrier shaft 37A forms a columnar shape around the axis line Ar. The external gear carrier shaft 37A extends from the external gear 17A to the input side in the axial direction. The input side part of the external gear carrier shaft 37A is inserted into the inner circumferential side of the cylindrical input side planetary gear carrier shaft 27Ai.

Even with the variable-speed speed-up mechanism 1 having the above-described transmission device 10A, similar to the first embodiment, by controlling the rotational speed of the variable-speed electric motor 71, it is possible to prevent the output shaft Ao from rotating reversely. In addition, it is possible to prevent the constant-speed electric motor 51 from rotating reversely.

In addition, the gear which meshes with the planetary gears 15 and 15A may be either the internal gear 17 as in the first embodiment or the external gear 17A as in the second embodiment, but the number thereof is not limited to the configuration of the embodiment. Therefore, for example, the gear which meshes with the planetary gear 15 may have two or more internal gears 17 as in the first embodiment. In addition, the gear which meshes with the planetary gear 15A may have only one or three or more external gears 17A as in the second embodiment.

REFERENCE SIGNS LIST

-   -   1 VARIABLE-SPEED SPEED-UP MECHANISM     -   10 TRANSMISSION DEVICE     -   11 SUN GEAR     -   12 SUN GEAR SHAFT     -   15,15A PLANETARY GEAR     -   17 INTERNAL GEAR (GEAR)     -   21,21A PLANETARY GEAR CARRIER     -   22,22A PLANETARY GEAR SHAFT     -   23,23A PLANETARY GEAR CARRIER MAIN BODY     -   27,27A PLANETARY GEAR CARRIER SHAFT     -   27 i, 27Ai INPUT SIDE PLANETARY GEAR CARRIER SHAFT     -   27 o, 27Ao OUTPUT SIDE PLANETARY GEAR CARRIER SHAFT     -   31 INTERNAL GEAR CARRIER     -   37 INTERNAL GEAR CARRIER SHAFT     -   41 TRANSMISSION DEVICE CASING     -   42 SUN GEAR BEARING     -   43,44 PLANETARY GEAR CARRIER BEARING     -   50 ELECTRIC DEVICE     -   51 CONSTANT-SPEED ELECTRIC MOTOR     -   52 CONSTANT-SPEED ROTOR     -   53 CONSTANT-SPEED ROTOR SHAFT     -   56 CONDUCTOR     -   61 CONSTANT-SPEED ELECTRIC MOTOR CASING     -   66 CONSTANT-SPEED STATOR     -   71 VARIABLE-SPEED ELECTRIC MOTOR     -   72 VARIABLE-SPEED ROTOR     -   73 VARIABLE-SPEED ROTOR SHAFT     -   74 SHAFT INSERTION HOLE     -   76 CONDUCTOR     -   81 VARIABLE-SPEED ELECTRIC MOTOR CASING     -   86 VARIABLE SPEED STATOR     -   100 ROTATIONAL SPEED CONTROL DEVICE     -   101 FREQUENCY CONVERSION UNIT     -   102 ROTATIONAL DIRECTION     -   110 POWER SOURCE LINE     -   111 VARIABLE-SPEED ELECTRIC MOTOR SWITCH     -   112 CONSTANT-SPEED ELECTRIC MOTOR SWITCH     -   120 CONTROL UNIT (CONTROL DEVICE)     -   121 RECEPTION UNIT     -   122 INTERFACE     -   123 OPERATION UNIT     -   Ac CONSTANT-SPEED INPUT SHAFT     -   Ao OUTPUT SHAFT     -   Ar AXIS LINE     -   Av VARIABLE-SPEED INPUT SHAFT     -   C COMPRESSOR     -   R1 FIRST DIRECTION     -   R2 SECOND DIRECTION     -   17A EXTERNAL GEAR (GEAR)     -   31A EXTERNAL GEAR CARRIER     -   37A EXTERNAL GEAR CARRIER SHAFT     -   151A FIRST PLANETARY GEAR (PRIMARY GEAR)     -   152A SECOND PLANETARY GEAR (SECONDARY GEAR) 

What is claimed is:
 1. A variable-speed speed-up mechanism, comprising: an electric device which is configured to generate a rotation driving force; and a transmission device which is configured to change the speed of the rotation driving force generated by the electric device and to transmit the rotation driving force to a target to be driven, wherein the transmission device includes a sun gear which is configured to rotate around an axis line, a sun gear shaft which is fixed to the sun gear and extends in a axial direction around the axis line, a planetary gear which is configured to mesh with the sun gear and to revolve around the axis line and to rotate around a center line thereof, a gear of which a plurality of teeth are arranged in an annular shape around the axis line, and which is configured to mesh with the planetary gear, a planetary gear carrier which has a planetary gear carrier shaft that extends in the axial direction around the axis line and supports the planetary gear to be capable of revolving around the axis line and to be rotatable around the center line of the planetary gear itself, and a gear carrier which has a gear carrier shaft that extends in the axial direction around the axis line and supports the gear to be rotatable around the axis line, wherein the sun gear shaft forms an output shaft which is configured to connect to the target to be driven, the gear carrier shaft forms a constant-speed input shaft, and the planetary gear carrier shaft forms a variable-speed input shaft, wherein the electric device includes a constant-speed electric motor having a constant-speed rotor that is configured to rotate the constant-speed input shaft of the transmission device in a second direction, a variable-speed electric motor having a variable-speed rotor which is connected to the variable-speed input shaft of the transmission device, which rotates the output shaft at the maximum rotational speed by rotating the variable-speed rotor at the maximum rotational speed in a first direction opposite to the second direction, at least two rotational speed sensors among an output shaft rotational speed sensor which measures a rotational speed ωs of the output shaft, a variable-speed electric motor rotational speed sensor which measures a rotational speed ωh of the variable-speed electric motor, and a constant-speed electric motor rotational speed sensor which measures a rotational speed ωi of the constant-speed electric motor, and a control device capable of calculating the rotational speed Os of the output shaft and the rotational speed ωh of the variable-speed electric motor from a measured value of the rotational speed sensor, and wherein, when a ratio ωs/ωi of the rotational speed ωs of the output shaft to the rotational speed ωi of the constant-speed electric motor is U, and when a ratio ωc/ωh of a rotational speed ωc of the planetary gear carrier to the rotational speed ωh of the variable-speed electric motor is P, in a case of ωs<0, the control device calculates a command value ωh′ of the rotational speed of the variable-speed electric motor to satisfy ωh′=ωh−ωs/P/(1+U), and controls the variable-speed electric motor by the command value ωh′.
 2. The variable-speed speed-up mechanism according to claim 1, wherein, in a case of ωs/P/(1+U)<ωh, the control device calculates the command value ωh′ of the rotational speed of the variable-speed electric motor to satisfy ωh′=ωs/P/(1+U), and controls the variable-speed electric motor by the command value ωh′.
 3. The variable-speed speed-up mechanism according to claim 1, wherein the variable-speed rotor has a cylindrical shape around the axis line and the constant-speed input shaft is inserted into a shaft insertion hole penetrating in an axial direction.
 4. The variable-speed speed-up mechanism according to claim 1, wherein the gear is an internal gear, and wherein the gear carrier shaft is an internal gear carrier shaft.
 5. The variable-speed speed-up mechanism according to claim 1, wherein the gear is an external gear, wherein the gear carrier shaft is an external gear carrier shaft, wherein the planetary gear includes a primary gear which meshes with the external gear and a secondary gear which meshes with the sun gear, and wherein the planetary gear carrier coaxially supports the primary gear and the secondary gear.
 6. The variable-speed speed-up mechanism according to claim 2, wherein the variable-speed rotor has a cylindrical shape around the axis line and the constant-speed input shaft is inserted into a shaft insertion hole penetrating in an axial direction.
 7. The variable-speed speed-up mechanism according to claim 2, wherein the gear is an internal gear, and wherein the gear carrier shaft is an internal gear carrier shaft.
 8. The variable-speed speed-up mechanism according to claim 3, wherein the gear is an internal gear, and wherein the gear carrier shaft is an internal gear carrier shaft.
 9. The variable-speed speed-up mechanism according to claim 6, wherein the gear is an internal gear, and wherein the gear carrier shaft is an internal gear carrier shaft.
 10. The variable-speed speed-up mechanism according to claim 2, wherein the gear is an external gear, wherein the gear carrier shaft is an external gear carrier shaft, wherein the planetary gear includes a primary gear which meshes with the external gear and a secondary gear which meshes with the sun gear, and wherein the planetary gear carrier coaxially supports the primary gear and the secondary gear.
 11. The variable-speed speed-up mechanism according to claim 3, wherein the gear is an external gear, wherein the gear carrier shaft is an external gear carrier shaft, wherein the planetary gear includes a primary gear which meshes with the external gear and a secondary gear which meshes with the sun gear, and wherein the planetary gear carrier coaxially supports the primary gear and the secondary gear.
 12. The variable-speed speed-up mechanism according to claim 6, wherein the gear is an external gear, wherein the gear carrier shaft is an external gear carrier shaft, wherein the planetary gear includes a primary gear which meshes with the external gear and a secondary gear which meshes with the sun gear, and wherein the planetary gear carrier coaxially supports the primary gear and the secondary gear. 